Accountants from PwC are now investigating the accounting irregularities at the business.

The company also said on Wednesday it would investigate why grant of share options to Mr Marsh and chief executive Paul May were not disclosed in its financial statements.

This comes after press speculation highlighted Mr May and Mr Marsh sold two tranches of shares each in 2018 but the 2017 financial report only shows one grant of long-term incentive plan (LTIP) options, which dates back to 2014.